Usain Bolt's Physics

I found this derivation of Usain Bolt's race equations and would like to know your opinion regarding the analysis (especially the differential equation for the power). Is it oversimplified or just fine?

I don't know the math that well, but I do know running and the vid attributes Bolt's top end speed in the constant speed phase of the run, from 40 through 100 meters, as the result of an equilibrium between the ground reaction force moving him forward and wind resistance as a force to the rear. That's a crock. After 40 meters Bolt has physically reached his biomechanical and physiological limit in his ability to increase the two primary variables related to running speed: stride length and stride frequency. Wind resistance does have a small effect, but I guarantee that if Bolt was able to increase his stride frequency by any amount that would transfer directly to his speed. Wind resistance as a function of terminal velocity pertains to free falling objects or perhaps jet aircraft, but this analysis was done by a math geek and not an athletic coach.